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How Does Cable Internet Work?

Picture of internet cord and modem

Is cable internet the best internet solution? Find out.

Getting an internet subscription through your cable service is a simple and cost-effective way to get a high-speed internet connection. Cable internet uses the existing lines for your cable TV to provide fast, reliable service, meaning  you can browse the web and watch your favorite TV shows at the same time, all over a single cable and through a single provider. Let’s break down how this internet service works and whether it’s right for you.

The science behind cable internet

Cable internet draws its name from the coaxial cable that makes all this data transfer possible. A coax cable is a traditional analog wire used to transmit cable television, similar to a landline phone. These copper wires lead from your property to a neighborhood node, and eventually to your service provider, which may be several miles away. Your cable modem sends and receives an electrical signal over the wires, using a few megahertz (MHz) of signal space at a time.

Here’s a pretty great video to break down the science behind cable internet:


Understanding bandwidth

The amount of signal space available is known as bandwidth. Bandwidth applies to your individual connection, and to the rest of the cable connections on your block. In almost all cases, you and your neighbors share a large pool of bandwidth stemming from a single neighborhood node.

Cable internet is only as fast as your cable network’s bandwidth allows. Bandwidth can be limited by the amount of internet use in your neighborhood, the amount of data you personally use, or the amount you’re paying for your internet service. Your TV channels only use up a small fraction of the available bandwidth of a typical coaxial cable, leaving enough left over for your internet connection.

Television signals are a one-way connection, from your service provider to the glowing box in your living room. Your internet service, however, requires data transmission in both directions. Your cable modem translates incoming signals, and your service provider’s cable modem termination system (CMTS) handles the data you’re sending back. Many traditional coaxial cables are now interwoven with fiber optic cable, dramatically increasing bandwidth to match users’ ever-increasing data loads.

Lynda has a great video explaining bandwidth:


Choosing your cable internet

If your home has a cable television connection, your service provider can almost always add internet service to your existing bill. While your cable internet uses the same cables as your television service, it’s often not necessary to subscribe to cable TV to get cable internet; most providers offer a standalone internet service. If you are looking for additional TV channels, it’s usually cheapest to bundle TV and internet with a single provider.

Connection speed

Your connection speed will depend heavily on your neighborhood’s bandwidth. In order to ensure fair service, the maximum bandwidth in a neighborhood is distributed evenly to all customers. If you’re a heavy user, you may see some restrictions on your internet use once you reach a certain limit, also known as a data cap.

Cable providers that specialize in high-speed internet often use a hybrid fiber-coax network (HFC), which adds fiber optic cable to your coax cable to dramatically increase bandwidth. Fiber optic cable transmits data using light instead of an electrical signal. Combining fiber and coax cable allows for significantly faster data transmission when compared to coax cable alone. These high-capacity cables may extend just to your neighborhood’s node, or they may reach all the way to your house.

How does cable internet stack up?

Because of the vast differences between regions, there isn’t a clear winner between cable internet, DSL, and satellite. Fiber connections that don’t rely on a coax cable have some of the fastest data transfer speeds available and offer incredible bandwidth, but access to this type of connection is limited to only a handful of urban areas in the U.S.

The FCC has a great chart that breaks down loading times by internet provider. You’ll notice that cable providers like Time Warner Cable and Comcast have significantly faster load times than DSL providers like Verizon and Frontier.

chart of internet speeds

Source: Federal Communications Commission


Short of a power outage, cable internet is very reliable. It isn’t subject to interruptions during bad weather like satellite internet. There can be issues with incorrectly installed cables, corroded cable hardware, or damage to the cable itself, which makes choosing a reliable service provider all the more important. In most cases, these issues will be corrected by your provider.

Potential issues with cable internet

In remote regions of the United States, you may run into a situation where local cable providers haven’t laid coax or fiber optic cable to your neighborhood. In this case, it may be more cost-efficient to go with a satellite or wireless internet provider.

In rare cases, you can pay your cable provider to run a cable from the nearest node to your property. This can be prohibitively expensive, in some cases costing as much as $20 per foot. There’s no guarantee the cable company will be willing to run a new cable, even if you’re willing to pay, so it’s important to make arrangements prior to moving into a new property.

Who provides the best cable internet service?

Again, cable internet service can vary greatly, even from one neighborhood to the next. With multiple service providers and regionally variable connection speeds and bandwidth, you really need to investigate all the connection options available for your property. Identify what your internet needs are, and you’ll be able to compare different providers to find the best intersection of price, speed, and reliability.